/*********************************************************************************
 *                                                                               *
 * The MIT License (MIT)                                                         *
 *                                                                               *
 * Copyright (c) 2015-2022 aoju.org OSHI and other contributors.                 *
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package org.aoju.bus.health.builtin.software;

import org.aoju.bus.core.annotation.ThreadSafe;
import org.aoju.bus.health.Memoize;

import java.util.function.Supplier;

/**
 * A process is an instance of a computer program that is being executed. It
 * contains the program code and its current activity. Depending on the
 * operating system (OS), a process may be made up of multiple threads of
 * execution that execute instructions concurrently.
 *
 * @author Kimi Liu
 * @version 6.5.0
 * @since Java 17+
 */
@ThreadSafe
public abstract class AbstractOSProcess implements OSProcess {

    private final Supplier<Double> cumulativeCpuLoad = Memoize.memoize(this::queryCumulativeCpuLoad, Memoize.defaultExpiration());

    private final int processID;

    protected AbstractOSProcess(int pid) {
        this.processID = pid;
    }

    @Override
    public int getProcessID() {
        return this.processID;
    }

    @Override
    public double getProcessCpuLoadCumulative() {
        return cumulativeCpuLoad.get();
    }

    private double queryCumulativeCpuLoad() {
        return getUpTime() > 0d ? (getKernelTime() + getUserTime()) / (double) getUpTime() : 0d;
    }

    @Override
    public double getProcessCpuLoadBetweenTicks(OSProcess priorSnapshot) {
        if (priorSnapshot != null && this.processID == priorSnapshot.getProcessID()
                && getUpTime() > priorSnapshot.getUpTime()) {
            return (getUserTime() - priorSnapshot.getUserTime() + getKernelTime() - priorSnapshot.getKernelTime())
                    / (double) (getUpTime() - priorSnapshot.getUpTime());
        }
        return getProcessCpuLoadCumulative();
    }

    @Override
    public String toString() {
        StringBuilder builder = new StringBuilder("OSProcess@");
        builder.append(Integer.toHexString(hashCode()));
        builder.append("[processID=").append(this.processID);
        builder.append(", name=").append(getName()).append(']');
        return builder.toString();
    }

}
